According to prior art there are known arrangements of battery modules wherein the battery modules each comprise an energy store. The battery modules are connected in series, and a predetermined current is applied to them by a charging device. In the course of the charging process the problem exists that the individual energy stores are charged differently due to the different ageing properties, and that an undesirable overcharging of individual energy stores can occur until the required charging voltage of the arrangement as a whole is reached.
To this end, in prior art there is proposed an arrangement with a number of energy stores, wherein the output voltage of each of the energy stores is carried to a control unit for controlling or driving a converter. When a predetermined maximum voltage, maximum charge, or maximum temperature for an energy store is exceeded, the control unit activates a converter the primary side of which is connected in parallel to the energy store. One of the two connections of the secondary side of the converter is connected with the system ground. The respective other connection of the secondary side of the converter is connected via a diode with the respective other connection of the charging device and the other pole of the energy store.
It is disadvantageous in prior art that for the energy discharge from the individual energy stores there are required two lines to a respective one of the two ends of the battery modules connected in series, respectively. There is required a large number of cables or wires as well as a large amount of work for their connection. In particular in the automotive sector, the routing of cable or wire harnesses is labor-intensive and cost-intensive. Moreover, the cables have a high mechanical stability and high-voltage strength. In mass production, the use of a plurality of cables is costly.
Proceeding from prior art, the objective task is to create a battery module which is easy to be cabled or wired and which manages with little external cabling or wiring and enables returning of the excess energy from the already charged battery modules.